I don't believe that this is a great idea, and nor will it work particularly well. Also, without seeing what elements you're using, I'm going to guess, with the following:
<p>Something not to copy...<img src="path/to/image.png" /></p>
CSS:
p {
position: relative;
}
p img {
position: absolute;
top: 0;
left: 0;
right: 0;
bottom: 0;
width: 100%;
height: 100%;
}
JS Fiddle demo.
A slightly easier way:
p {
-webkit-user-select: none;
-khtml-user-select: none;
-moz-user-select: none;
-o-user-select: none;
user-select: none;
}
JS Fiddle demo.
A slightly more reliable way (that doesn't rely on updated/'modern' browsers, but which isn't requested in your question, as it uses JavaScript:
var paras = document.getElementsByTagName('p');
for (var i=0, len=paras.length; i<len; i++){
paras[i].onmousedown = function(){
return false;
};
}
JS Fiddle demo.